RFC 1349 Type of Service July 1992 5. Use of the TOS Field in the Internet Protocols ............. 6 5.1 Internet Control Message Protocol (ICMP) ............... 6 5.2 Transport Protocols .................................... 7 5.3 Application Protocols .................................. 7 6. ICMP and the TOS Facility .................................. 8 6.1 Destination Unreachable ................................ 8 6.2 Redirect ............................................... 9 7. Use of the TOS Field in Routing ............................ 9 7.1 Host Routing ........................................... 10 7.2 Forwarding ............................................. 12 8. Other consequences of TOS .................................. 13 APPENDIX A. Updates to Other Specifications ................... 14 A.1 RFC-792 (ICMP) ......................................... 14 A.2 RFC-1060 (Assigned Numbers) ............................ 14 A.3 RFC-1122 and RFC-1123 (Host Requirements) .............. 16 A.4 RFC-1195 (Integrated IS-IS) ............................ 16 A.5 RFC-1247 (OSPF) and RFC-1248 (OSPF MIB) ................ 17 APPENDIX B. Rationale ......................................... 18 B.1 The Minimize Monetary Cost TOS Value ................... 18 B.2 The Specification of the TOS Field ..................... 19 B.3 The Choice of Weak TOS Routing ......................... 21 B.4 The Retention of Longest Match Routing ................. 22 B.5 The Use of Destination Unreachable ..................... 23 APPENDIX C. Limitations of the TOS Mechanism .................. 24 C.1 Inherent Limitations ................................... 24 C.2 Limitations of this Specification ...................... 25 References ..................................................... 27 Acknowledgements ............................................... 28 Security Considerations ........................................ 28 Author's Address ............................................... 28 Almquist